Patent GB-189701594-A (GB)
Title: Improvements in Spring Locks and in Detectors therefor.
Inventor: TURNER EDWIN JOHN
Filed: 1897-01-20
Granted: 1898-01-08
Abstract: 1594. Turner, E. J. Jan. 20. Locks, key.-Relates to a spring detector lock for drawers, doors, boxes, &c. A plate d, Fig. 1, carrying a number of spring levers j, is pivoted on a ring d<3>, and turned by a key. Figs. 12 and 13, which engages in lugse. A pin behind the pin d<1> operates a lever g pivoted on the lock plate a and engaging with the spring bolt b. The key bit l has a number of projections l<1> with inclined surfaces adapted to engage with similar surfaces k<4> on arms k<3> projecting from the levers j, and, when the key is pressed in, to bring arms k on the levers in register with apertures k<2> in a guard-plate k<1>, allowing the plate d to be turned by the key and the bolt retracted. The bolt is blocked by a pivoted spring arm n, which is moved aside by a tooth n<6> on the plate d when the latter is turned, a lug n<3> on the arm passing through a slot in a lug n<5> on the bolt and holding the latter retracted till disengaged by a push-button from the outside. A detector, Fig. 10, is provided to show when any of the levers have been moved too far by tampering with a false key, and to prevent such levers from resuming their normal positions till reset by the proper key. It consists of a number of spring plates m having projections which can pass through apertures in the plate d, but are normally prevented by an arm m<3> which engages under the ends of the plates. This arm is carried on a pin passing through the plate d and carrying on the other side a similar arm m<4>, Fig. 2. The lower sides of the lever arms k<3> have projections, which, when any of the levers are moved too far, displace the arm m<4>, and, consequently, the arm m<3>, before the levers return. The displacement of the arm m<3> prevents the plate d from being operated in the proper direction when the proper key is inserted, owing to the arm being blocked by a stop m<5> on the lock case, thus showing the lock to have been tampered with. The detector is reset by first turning the key in the wrong direction, when a stop m<6> on the plate operates a pivoted arm m<7> on the lock case to restore the arm m<3>, the spring plates being lifted by the engagement of the projections on the plates and levers to permit the arm m<3> to pass under. In a modification, the lever g is mounted between two projections on the plate d, and the bolt is prevented from being pushed back by a pawl on it engaging the end of the lever. This pawl is capable of an axial movement on its pivot to allow the plate d to return and the key to be withdrawn while the bolt is retracted. The bolt is held in the retracted position by a hooked leaf spring, released by a push-button &c. To avoid the use of long keys for thick doors, a cylinder s, Figs. 19 and 20, is applied to the lock case, and a tube s', corresponding to the key bit, and carrying a number of sliders s<2>, slides in it. The inner ends of these sliders are formed to correctly move the lever arms k<3> when moved by inserting the key, the key bit turning the tube s<1> and operating the bolt. The shape of the key bit or the keyhole may be varied for different locks, and the opposite portions of the key bit are of different shapes to prevent the key from being wrongly inserted. The staple of a box lock may have a sliding plate on one of the eyes, which may be moved to block the eye and prevent the bolt from being released from its retracted position when the lid is merely pushed to.